This invention relates to tufting machines and more particularly to a tufting machine having an improved slidable needle plate for shifting the backing fabric laterally to laterally displace the individual yarn ends between the various longitudinal rows.
The art of tufting incorporates a plurality of yarn carrying spaced needles extending transversely across the machine and reciprocated cyclically to penetrate and insert pile into a backing fabric fed longitudinally beneath the needles. During each penetration of the backing fabric a row of pile is produced transversely across the backing. Successive penetrations result in a longitudinal row of pile produced by each needle. This basic method of tufting limits the aesthetic appearance of tufted carpet so produced.
Methods have been devised which effect relative shifting between the needles and the backing fabric which provide patterning capabilities and which break-up the noticeable alignment of the longitudinal rows that detract from the appearance of the carpet. Moreover, when using yarns of different color and different needles the shifting selectively transfers yarns of one color into a row normally having a different color. One such method is illustrated in U.S. Pat. of Card, No. 3,30l,205 which provides a needle plate supported for movement laterally of the machine and provides a cam operated linkage for shifting the needle plate in accordance with a pattern. Needle plate fingers are provided to secure the backing fabric to the needle plate for lateral movement while allowing longitudinal movement of the fabric over the needle plate and fingers. It has now been found that the grip provided by this construction especially when the newer backing fabric materials are used is not sufficient enough to obtain more than very limited lateral movement of the backing when the needle plate is shifted laterally. Moreover since the prior slidable needle plate support construction provided a gib bearing between the needle plate and the bed plate rail, additional limitations as to rigidity and sliding friction limit the extent of needle plate shifting.